1. Field of the Invention
The invention relates to a measuring system, which uses a light beam generated by a light source for measuring the position in space of an object, which may for example be the arm of a robot, a vehicle moveable along a track, or a head of a coordinate positioning machine.
An example of such a system is a laser interferometer, used to measure the position of a head of a coordinate positioning machine (eg: a coordinate measuring machine or machine tool). Typically the interferometer measures the head position to an accuracy of the order of a micron. Thus, phenomena such as for example temperature variation, small misalignments in the beam angle, small vocal variations in the refractive index of air, or vibration of the head can greatly affect the accuracy of any measurement made with the interferometer.
2. Description of the Art
It is known to provide a weather station in the vicinity of an optical measuring system, in order to monitor the ambient conditions; correction (if required) may thus be made to the measurement. Such weather stations however, only determine the value of the parameters affecting the ambient conditions in their immediate vicinity It may be necessary in order to achieve a required degree of accuracy, and/or in the case where the position of the object is to be measured in several different positions, to monitor such parameters, (and also one or more additional parameters discussed above) in several places.